ieee1394: adjust code formatting in highlevel.c

Replace spaces by tabulators, wrap lines at 80 columns, delete some
blank lines and superfluous braces.  Collapse some if()-within-if()
constructs.  Replace a literal CSR address by its preprocessor constant.

Signed-off-by: Stefan Richter <[email protected]>
Signed-off-by: Ben Collins <[email protected]>